Palmitate, oxidation vision

Retinol is found only in foods of animal origin and a small number of bacteria, mainly as the ester retinyl palmitate. Retinoic acid is a metabolite of retinol and has important biological activities in its own right. The oxidation of retinaldehyde to retinoic acid is irreversible, and retinoic acid cannot be converted to retinol in vivo, and does not support either vision or fertility in deficient animals. 

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